1. Field of the Invention
The present invention relates to comestibles such as chewing gum containing .gtoreq.2% moisture and made with L-aspartyl-L-phenylalanine methyl ester (APM or aspartame) in which the aspartame has been significantly stabilized against decomposition, during its shelf life, into decomposition products such as diketopiperazine, by being formulated with aqueous hydrogenated starch hydrolystate that has been cooked to achieve a moisture content of about 10.+-.6%. Glycerine may also be added with the cooked hydrogenated starch hydrolysate.
2. Description of the Prior Art
Aspartame which is used extensively in many types of sugarless foodstuffs, or other comestible products, such as chewing gum, is known to readily decompose in the presence of moisture into decomposition products such as diketopiperazine which causes a significant loss in the sweetness properties of such products during their shelf lives. Many attempts have been made by those producing the various types of products in which aspartame is used in order to provide means for stabilizing the aspartame against such decomposition processes. Such means have included encapsulating the aspartame in various film forming materials (U.S. Pat. Nos. 3,929,988, 4,384,004 and International Patent Application WO No. 84/0320), or by saturating an aqueous dispersing agent used in the product with the aspartame (EPA 102,032), or by formulating the product with stabilizing agents for the aspartame such as commercially available aqueous hydrogenated starch hydrolysate which has a moisture content of about 20 to 35%. (see in this regard U.S. patent applications Ser. No. 677,717 filed Dec. 4, 1984 in the names of D. R. Friello, et al, and entitled "Comestible Containing Moisture and Shelf Storage Stabilized L-Aspartic Acid Derivative", and refiled as Ser. No. 865,493 on May 20, 1983 and Ser. No. 677,716 filed Dec. 4, 1984 in the names of D. R. Friello et al. and entitled "Comestible Containing Moisture, CaCO.sub.3 and Shelf Storage Stabilized L-Aspartic Acid Derivative", and refiled as Ser. No. 867,821, on May 27, 1986."
Each of such various prior art means, however, have certain drawbacks. The encapsulation means requires a separate, time-consuming and relatively expensive procedure for encapsulating the aspartame which amounts to a separate processing operation.
Saturating the moisture content of a product with aspartame requires the use of excess amounts of the aspartame needed to achieve a certain level of sweetness. Since aspartame is a relatively expensive material, this proposed solution to the aspartame decomposition procedure is a rather expensive one. Further, it does not prevent the decomposition of the aspartame into undesired decomposition products such as diketopiperazine.
Although the use of aqueous hydrogenated starch hydrolysate having a moisture content of 20 to 35% as an aspartame stabilizer, as taught in said U.S. Ser. Nos. 677,716, 677,717, 867,821 and 865,493 does provide a fair degree of long term aspartame stability in chewing gum, a significant degree of improvement in such stabilizing action is still desired for commercial reasons, i.e., because of the relatively high cost of the aspartame, and to extend the shelf life of the products made with aspartame.
It is also desired to use aspartame in products having relatively high moisture contents in order to avoid the need for stringent anhydrous operating conditions that are required when producing chewing gum products having very low moisture contents, i.e., less than 1 to 2%. See in this regard European Patent Application 82670 and International Patent Application WO No. 84-10693.
Further, various of these prior art chewing gum products which have such very low moisture contents, i.e., of about 1 to 2%, also have relatively low equilibrium relative humidity (ERH) values, i.e., of the order to about 10 to 25. During the storage of such products under ambient conditions of about 40 to 70% relative humidity and about 20.degree. to 30.degree. C., the (low value) ERH properties of such products will cause such products to absorb relatively large amounts of water from the atmosphere.
Such increased amounts of water will lead to a more accelerated rate of decomposition of any unprotected APM therein; and will adversely affect other qualities of the products.
Thus, such products having very low ERH values would require that they be processed amd wrapped under special atmospheric conditions of low humidity and controlled temperature. Such conditions are expensive and difficult to maintain.
Equilibrium relative humidity (ERH) or relative vapor pressure is the humidity at which a foodstuff neither gains nor loses moisture and the figure is expressed as a percentage. A discussion of ERH relative to food products and a method for the determination thereof is to be found in "Chocolate, Cocoa and Confectionery," Science and Technology, Second Edition, 1980, Bernard W. Minifie, AVI Publishing Co., Inc. Westport, Conn., U.S.A., Appendix I, pp. 672-677 (the disclosure of which is incorporated herein by reference). The test procedure disclosed in such publication is the one used for testing and evaluating the compositions disclosed herein.
U.S. Pat. No. 4,248,895 discloses the preparation of a dried non-hygroscopic free flowing powder that is made by drying a higher polyalcohol, such as hydrogenated starch hydrolysate, with a concentrated protein extract. The dried material has a moisture content of about 2-6% and may be used as a sweetener in confections such as chewing gum to provide products having prolonged shelf life in terms of retained flexibility and softeners. Other non-sugar sweeteners may be used with the dried, powdered, higher alcohol sweetener such as L-aspartyl-L-phenylalanine. The dried hydrogenated starch hydrolysate may also be used in combination with hydrogenated starch hydrolysate syrup having a moisture content of 15 to 40%.
U.S. Pat. No. 4,382,962 discloses the preparation of sugarless chewing gum made with a specific hydrogenated starch hydrolysate composition that is designed to replace all or a portion of the mannitol previously used with xylitol and/or sorbitol in such products. Cyclamates and the salts of saccharin may be also used in such products when the product contains a liquid filler (column 4, lines 20-45).
Cooked hydrogenated starch hydrolysate which has a moisture content of about 8.+-.4% has also been proposed for use in flexible sugarless chewing gum. See in this regard U.S. patent application Ser. No. 717,765 filed Mar. 29, 1985 in the names of Thomas J. Carroll et al. and entitled "Flexible Sugarless Chewing Gum", and the continuation-in-part of said U.S. Ser. No. 717,765 filed Mar. 14, 1986 as Ser. No. 840,300.
Therefore, it has not been readily possible, heretofore, to economically provide a means for stabilizing aspartame in chewing gum products having a relatively high moisture content so as to provide for more optimum stabilization effects.
An object of the present invention is to provide comestibles such as chewing gum products containing .gtoreq.2% moisture and sweetened, at least in part, by aspartame, and wherein relatively high levels of aspartame stability are achieved during long term storage of the products.
A further object of the present invention is to provide such comestibles as have a relatively high ERH value.